Sticks and stones may break your bones but words will break your brain

“Sticks and stones may break my bones but words will never hurt me.” Sounds familiar? You may have been taught this witty maxim to fend off bullies during the glorious years that are high school. Since then, bullying has become a big deal: its often-devastating consequences are more than ever in the public eye. We already know that childhood abuse in many different forms (sexual abuse, physical abuse, witnessing domestic violence) can have long-lasting impacts. For example, sufferers are found to be more susceptible to depression and suicide, and more likely to engage in fights, do drugs and use a weapon. But what about verbal abuse from peers?

To evaluate the effects of peer verbal abuse on the brain and behavior, a team of researchers studied over 800 young adults who had no history of any of the big confounding factors such as exposure to domestic violence, sexual abuse, or physical abuse. The participants were asked to fill out surveys about how much verbal abuse they experienced from peers at school as well as surveys with more general questions about mood, behavior and psychiatric symptoms.

The results show that the more peer verbal abuse one is exposed to during school, the more likely they are to experience anxiety, depression, anger and drug use. As it turns out, verbal abuse from peers is just as bad as verbal abuse from parents in generating these consequences. As well, researchers found that peer verbal abuse that occurs during middle school years (ages 11-14) has the most significant impact (compared with elementary school and high school). I find that surprising, as I remember high school being much worse than middle school, but apparently it has to do with the timeline of brain development, not my personal feelings about high school.

To dig a little deeper, the researchers selected 63 participants who had experienced varying degrees of peer verbal abuse and had them undergo a brain scan (MRI). They found that participants who had been exposed to a lot of peer verbal abuse displayed abnormalities in their corpus callosum, a big bunch of white matter fibers that connect the left and right sides of your brain. The researchers suggest that this abnormality may explain some of the behaviors and symptoms associated with the abuse (such as depression).

While this study convincingly highlights the impact of bullying on the brain and brain function, there are a few things to keep in mind. Repeat after me: correlation does not mean causation. That undergoing bullying is associated with abnormalities in the brain does not mean that bullying necessarily caused these abnormalities. More studies will be needed to uncover that link. As well, the study is retrospective, meaning the authors “go back in time” by asking the participants to remember events from years ago. This can sometimes lead to faulty recalls or false associations. Lastly, I find it a bit strange that the researchers have not looked at the hippocampus of the participants. You may remember that the hippocampus is a brain region important for memory, but it is also involved in emotions, and it has been shown to be susceptible to other forms of abuse. I’m hoping the bullying-hippocampus link will be looked at in a future study.

Overall, though, the study reminds us that bullying is an important and potent childhood stressor. Sticks and stones it is.

Reference: Hurtful words: association of exposure to peer verbal abuse with elevated psychiatric symptom scores and corpus callosum abnormalities. (2010) Teicher MH et al. Am J Psychiatry 167(12):1464-71.

Brains and birthdays

We hear a whole lot about new brain imaging techniques lately. It seems like imaging studies are constantly revealing new pieces of information about the brain: what part of the brain is responsible for our morality, what happens when you fall in love, and so on. One of the main techniques used in these studies is called functional magnetic resonance imaging (fMRI). Unlike a regular MRI, which takes a static image, fMRI can give us images of a dynamic process: the flow of oxygenated blood in the brain. Presumably, when one region of your brain is activated, the brain cells require more oxygen, so more oxygenated blood flows to that region, and this can be seen and measured using fMRI.

While it may be very interesting to find out what happens to your brain when you fall in love, we have yet to see real clinical benefits from these fancy new brain scans. Brain disorders and diseases, such as depression and Alzheimer’s disease, still cannot be diagnosed using fMRI. One of the reasons for this limitation is that an fMRI scan for a single person really doesn’t tell us much: we can only gain insights from this technique if we look at groups of people, and compare averages. To this day, this problem has really limited the potential of fMRI for diagnosing brain diseases. However, a recent publication in the journal Science suggests that fMRI may soon be clinically relevant.

The researchers were interested in finding an application where a single brain scan could provide information about the individual. They chose to assess the maturity of the brain, and used chronological age as a reference measure. Instead of using regular fMRI, the researchers used an even fancier version, fcMRI (fc stands for “functional connectivity”). This type of imaging measures the spontaneous activity between brain regions. How strongly different brain regions interact with each other is thought to be shaped by all the experiences one accumulates over time, hence the potential to determine maturity from these kinds of measures.

Participants aged seven to 30 years old were asked to undergo a five-minute brain scan. What followed was an extremely complex series of models and algorithms developed by the researchers to establish a “maturation curve”, from which they could then predict the maturity of a given brain based on where its scan fits along the curve.

Ultimately, it was established that yes, a single scan can provide information about the person’s brain: it can predict its maturity level. But couldn’t we already determine brain age just by looking at its shape? For the most part, yes. The reason this article is relevant is because quite a few brain diseases and disorders don’t have a signature shape (unlike tumors, for example, which can sometimes be spotted on a static image). Therefore, having a tool that allows us to assess brain function without having to compare large groups could become very valuable in the diagnosis of some brain disorders (provided we first determine the functional signature of these disorders).

As an interesting side note, the researchers' results suggest that on average, functional brain maturity levels out at about age 22. This obviously represents a physiological maturity level, not a cognitive maturity level, thank goodness. When I was 22, I used to think I knew everything. How I've "matured" since then!

Reference: Prediction of individual brain maturity using fMRI. Dosenbach N.U.F. et al. Science 329:1358-61 (2010).